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325,404 Matching Results

Start Over Decade 1990-1999

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Results: 1 - 24 of 325,404 next

(open access)

0.5 μm E/D AlGaAs/GaAs heterostructure field effect transistor technology with DFET threshold adjust implant

A doped-channel heterostructure field effect transistor (H-FET) technology has been developed with self-aligned refractory gate processing and using both enhancement- and depletion-mode transistors. D-HFET devices are obtained with a threshold voltage adjust implant into material designed for E-HFET operation. Both E- and D-HFETs utilize W/WSi bilayer gates, sidewall spacers, and rapid thermal annealing for controlling short channel effects. The 0.5 {mu}m E- HFETs (D-HFETs) have been demonstrated with transconductance of 425 mS/mm (265-310 mS/mm) and f{sub t} of 45-50 GHz. Ring oscillator gate delays of 19 ps with a power of 0.6 mW have been demonstrated using direct coupled FET logic. These results are comparable to previous doped-channel HFET devices and circuits fabricated by selective reactive ion etching rather than ion implantation for threshold voltage adjustment.

Date: April 1997

Creator: Baca, A. G.; Sherwin, M. E.; Zolper, J. C.; Shul, R. J.; Briggs, R. D.; Heise, J. A. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

D-0 End Calorimeter Warm Tube/TeV Dry Air Purge

This Engineering Note studies the design of the Dry Air Purge that is going to flow through the Warm Tube of the End Calorimeter of the D-O Calorimeter. The Tev tubes through the E.C. can be thought of as a cluster of concentric tubes: The Tev tube, the warm (vacuum vessel) tube, 15 layers of superinsulation, the cold (argon vessel) tube, and the Inner Hadronic center support tube. The Dry Air Purge will involve flowing Dry Air through the annular region between the Warm Tube and the Tev Beam Pipe. This air flow is intended to prevent condensation from forming in this region which could turn to ice under cryogenic temperatures. Any ice formed in this gap, could cause serious problems when these tubes are moved. The Air will flow through a Nylon Tube Fitting -1/4-inch I.D. to 1/8-inch male pipe thread (Cole Palmer YB-06465-15) see Drawing MC-295221 (Appendix A). This fitting will be attached to the Nylon 2-inch Tube-Wiper and Seal Assembly which is clamped to the ends of the Warm Tube (Appendix A). This note includes drawings and calculations that explain the setup of the Dry Air Purge and give the required information on the pressure drops through …

Date: August 14, 1991

Creator: Leibfritz, J. R.

Object Type: Report

System: The UNT Digital Library

(open access)

0-G experiments with advanced ceramic fabric wick structures

Both Air Force and NASA future spacecraft thermal management needs span the temperature range from cryogenic to liquid metals. Many of these needs are changing and not well defined and will remain so until goals, technology, and missions converge. Nevertheless, it is certain that high-temperature (> 800 K) and medium-temperature (about 450 K) radiator systems will have to be developed that offer significant improvements over current designs. This paper discusses experiments performed in the lower temperature regime as part of a comprehensive advanced ceramic fabric (ACF) heat pipe development program. These experiments encompassed wicking tests with various ceramic fabric samples, and heat transfer tests with a 1-m long prototype ACF water heat pipe. A prototype ceramic fabric/titanium water heat pipe has been constructed and tested; it transported up to 60 W of power at about 390 K. Startup and operation both with and against gravity examined. Wick testing was begun to aid in the design and construction of an improved prototype heat pipe, with a 38-{mu}m stainless steel linear covered by a biaxially-braided Nextel (trademark of the 3M Co., St. Paul, Minnesota) sleeve that is approximately 300-{mu}m thick. Wick testing took place in 1-g; limited testing in 0-g was initiated, …

Date: July 1991

Creator: Antoniak, Z. I.; Webb, B. J.; Bates, J. M.; Cooper, M. F. & Pauley, K. A.

Object Type: Article

System: The UNT Digital Library

(open access)

D-0 North End Cap Calorimeter Cold Test Results

The North endcap calorimeter vessel was recieved on July 1, 1990. A cooldown of the pressure vessel with liquid nitrogen was performed on July 10-11 to check the vessel's integrity. With the pressure vessel cold, the insulating vacuum was monitored for leaks. Through out the testing, the insulating vacuum remained good and the vessel passed the test. The cold test was carried out per the procedures of D-Zero engineering note 3740.220-EN-250. The test was very similar to the cold test performed on the Central Calorimeter in October of 1987. Reference D-Zero engineering notes 3740.210-EN-122, 3740.000-EN107, and 3740.210-EN-110 for information about the CC cold test. The insulating vacuum space was pumped on while equipment was being connected to the pressure vessel. Two hours after starting to pump with the blower the vacuum space pressure was at about 210 microns. Pumping on the vacuum space for the next 15 hours showed no progress and a leak detector was connected to the pumping line. A leak check showed a leak in a thermocouple feedthru on the vacuum space relief plate. After fixing the leak, the pressure dropped to 16 microns in less than one hour. A rate of rise test was performed starting …

Date: August 2, 1990

Creator: Michael, J.

Object Type: Report

System: The UNT Digital Library

(open access)

D-0 South End Cap Calorimeter Cold Test Results

The South endcap calorimeter vessel was moved into Lab A on Sept. 18, 1990. A cooldown of the pressure vessel with liquid nitrogen was performed on Sept. 26 to check the vessel's integrity. With the pressure vessel cold, the insulating vacuum was monitored for leaks. Through out the testing, the insulating vacuum remained good and the vessel passed the test. The cold test was carried out per the procedures of D-Zero engineering note 3740.220-EN-250. The test was very similar to the cold test performed on the Central Calorimeter in October of 1987. The test of the ECS was performed in the same manner using the same equipment as the ECN cold test. Reference D-Zero engineering notes 3740.210-EN-122, 3740.000-EN-I07, and 3740.210-EN-II0 for information about the CC cold test. Reference EN-260 for the results of the ECN cold test. The insulating vacuum space was pumped on while equipment was being connected to the pressure vessel. Two hours after starting to pump with the blower the vacuum space pressure was at about 40 microns. The pumping continued overnight (another 16 hours). In the morning the pressure was 11.5 microns. A rate of rise test was performed. With the pump valved off, the pressure …

Date: November 26, 1990

Creator: Rucinski, R.

Object Type: Report

System: The UNT Digital Library

A 1

Access: Use of this item is restricted to the UNT Community

Recording of Daniel Schachter's A 1. This piece uses traditional electronic technique and emphasizes on musical gestures. The sounds are mostly synthetically constructed and are heard throughout the piece.

Date: 1992

Creator: Schachter, Daniel, 1953-

Object Type: Sound

System: The UNT Digital Library

(open access)

[1/2 HP Maytag Restoration]

Article by Pettinger, Wesley E. about 1/2 HP Maytag Engine Restoration.

Date: January 13, 1997

Creator: Pettinger, Wesley E.

Object Type: Article

System: The UNT Digital Library

(open access)

1.2 MW klystron for Asymmetric Storage Ring B Factory

A cw klystron operating at 476 MHz has been developed jointly by SLAC and Varian Associates. The unique set of characteristics of this tube were strongly guided by requirements of the fast feedback necessary to prevent oscillations of the storage ring beams caused by the detuned accelerating cavity. This requires a combination of bandwidth and short group delay within the klystron. The RF feedback stabilization scheme also requires amplitude modulation making it necessary to operate the klystron about 10% below saturation. Performance specifications and initial operating results are presented.

Date: March 1995

Creator: Fowkes, W. R.; Caryotakis, G. & Doyle, E.

Object Type: Article

System: The UNT Digital Library

(open access)

1.4 Natural Gas Combustion

This document focus's on the use of natural gas as a major combustion fuel and offers information on firing practices, emissions, and controls.

Date: 1998

Creator: United States. Environmental Protection Agency.

Object Type: Text

System: The UNT Digital Library

(open access)

A 1. 5--4 Kelvin detachable cold-sample transfer system: Application to inertially confined fusion with spin-polarized hydrogens fuels

A compact cold-transfer apparatus for engaging and retrieving samples at liquid helium temperatures (1.5--4K), maintaining the samples at such temperatures for periods of hours, and subsequently inserting them in diverse apparatuses followed by disengagement, is described. The properties of several thermal radiation-insulating shrouds, necessary for very low sample temperatures, are presented. The immediate intended application is transportable target-shells containing highly spin-polarized deuterons in solid HD or D{sub 2} for inertially confined fusion (ICF) experiments. The system is also valuable for unpolarized high-density fusion fuels, as well as for other applications which are discussed. 9 refs., 6 figs.

Date: January 1, 1990

Creator: Alexander, N.; Barden, J.; Fan, Q. & Honig, A.

Object Type: Report

System: The UNT Digital Library

(open access)

A 1.5 GeV compact light source with superconducting bending magnets

This paper describes the design of a compact electron synchrotron light source for producing X-rays for medical imaging, protein crystallography, nano-machining and other uses up to 35 keV. The source will provide synchrotron light from six 6.9 tesla superconducting 60{degree} bending magnet stations. In addition the ring, contains conventional quadrupoles and sextupoles. The light source has a circumference of 26 meters, which permits it to be located in a variety of industrial and medical facilities.

Date: May 1995

Creator: Garren, A. A.; Cline, D. B.; Kolonko, J. J.; Green, M. A.; Johnson, D. E.; Leung, E. M. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

1.8.2.1.2 Site system engineering implementation Fiscal Year 1998 multi-year work plan

Manage the Site Systems Engineering process to provide a traceable, integrated, requirements-driven, and technically defensible baseline., Through the Site Integration Group, Systems Engineering ensures integration of technical activities across all site projects. Systems Engineering`s primary interfaces are with the Project Direction Office and with the projects, as well as with the Planning organization.

Date: October 3, 1997

Creator: Ferguson, J. E.

Object Type: Report

System: The UNT Digital Library

(open access)

1.8.3 Site system engineering FY 1997 program plan

The FY 1997 Multi-Year Work Plan (MYWP) technical baseline describes the functions to be accomplished and the technical standards that govern the work. The following information is provided in this FY 1997 MYWP: technical baseline, work breakdown structure, schedule baseline, cost baseline, and execution year.

Date: September 13, 1996

Creator: Grygiel, M. L.

Object Type: Report

System: The UNT Digital Library

(open access)

A 1.8 K test facility for superconducting RF cavities

To demonstrate the feasibility of superconducting RF technology for a high energy e{sup +}/e{sup {minus}} collider, a research and development program has begun with collaborators from Europe, Asia, and North America. The immediate goal of the R&D program is to build and operate a 50 meter-long linac at DESY with 1.3 GHz superconducting RF cavities at a temperature of 1.8 K - 2.0 K and an accelerating gradient of 15 MV/meter. The refrigeration for the test system at DESY initially will have a capacity of about 100 W at 1.8 K, distributed among three test cryostats. In a second step, refrigeration will be upgraded to 200 W at 1.8 K in order to supply the 50 meter test linac. This paper describes the cryogenics of this test system.

Date: April 1, 1994

Creator: Horlitz, G.; Knopf, U.; Lange, R.; Petersen, B.; Sellmann, D.; Trines, D. et al.

Object Type: Article

System: The UNT Digital Library

(open access)

1/12-Scale mixing interface visualization and buoyant particle release tests in support of Tank 241-SY-101 hydrogen mitigation

In support of tank waste safety programs, visualization tests were performed in the 1/12-scale tank facility, using a low-viscosity simulant. The primary objective of the tests was to obtain video records of the transient jet-sludge interaction. The intent is that these videos will provide useful qualitative data for comparison with model predictions. Two tests were initially planned: mixing interface visualization (MIV) and buoyant particle release (BPR). Completion of the buoyant particle release test was set aside in order to complete additional MIV tests. Rheological measurements were made on simulant samples before testing, and the simulant was found to exhibit thixotropic behavior. Shear vane measurements were also made on an in-situ analog of the 1/12-scale tank simulant. Simulant shear strength has been observed to be time dependent. The primary objective of obtaining video records of jet-sludge interaction was satisfied, and the records yielded jet location information which may be of use in completing model comparisons. The modeling effort is not part of this task, but this report also discusses test specific instrumentation, visualization techniques, and shear vane instrumentation which would enable improved characterization of jet-sludge interaction and simulant characteristics.

Date: October 1, 1993

Creator: Eschbach, E. J. & Enderlin, C. W.

Object Type: Report

System: The UNT Digital Library

(open access)

1/12-scale physical modeling experiments in support of tank 241-SY- 101 hydrogen mitigation

Hanford tank 241-SY-101 is a 75-ft-dia double-shell tank that contains approximately 1.1 M gal of radioactive fuel reprocessing waste. Core samples have shown that the tank contents are separated into two main layers, a article laden supernatant liquid at the top of the tank and a more dense slurry on the bottom. Two additional layers may be present, one being a potentially thick sludge lying beneath the slurry at the bottom of the tank and the other being the crust that has formed on the surface of the supernatant liquid. The supernatant is more commonly referred to as the convective layer and the slurry as the non-convective layer. Accumulation of gas (partly hydrogen) in the non-convective layer is suspected to be the key mechanism behind the gas burp phenomena, and several mitigation schemes are being developed to encourage a more uniform gas release rate (Benegas 1992). To support the full-scale hydraulic mitigation test, scaled experiments were performed to satisfy two objectives: 1. provide an experimental database for numerical- model validation; 2. establish operating parameter values required to mobilize the settled solids and maintain the solids in suspension.

Date: January 1, 1993

Creator: Fort, J. A.; Bamberger, J. A.; Bates, J. M.; Enderlin, C. W. & Elmore, M. R.

Object Type: Report

System: The UNT Digital Library

(open access)

1/12-scale physical modeling experiments in support of tank 241-SY- 101 hydrogen mitigation. Final report

Date: January 1993

Creator: Fort, J. A.; Bamberger, J. A.; Bates, J. M.; Enderlin, C. W. & Elmore, M. R.

Object Type: Report

System: The UNT Digital Library

(open access)

1/12-Scale scoping experiments to characterize double-shell tank slurry uniformity: Test plan

Million gallon double-shell tanks (DSTs) at Hanford are used to store transuranic, high-level, and low-level wastes. These wastes generally consist of a large volume of salt-laden solution covering a smaller volume of settled sludge primarily containing metal hydroxides. These wastes will be retrieved and processed into immobile waste forms suitable for permanent disposal. The current retrieval concept is to use submerged dual-nozzle pumps to mobilize the settled solids by creating jets of fluid that are directed at the tank solids. The pumps oscillate, creating arcs of high-velocity fluid jets that sweep the floor of the tank. After the solids are mobilized, the pumps will continue to operate at a reduced flow rate sufficient to maintain the particles in a uniform suspension. The objectives of these 1/12-scale scoping experiments are to determine how Reynolds number, Froude number, and gravitational settling parameter affect the degree of uniformity achieved during jet mixer pump operation in the full-scale double-shell tanks; develop linear models to predict the degree of uniformity achieved by jet mixer pumps operating in the full-scale double-shell tanks; apply linear models to predict the degree of uniformity that will be achieved in tank 241-AZ-101 and determine whether contents of that tank will …

Date: October 1994

Creator: Bamberger, J. A. & Liljegren, L. M.

Object Type: Report

System: The UNT Digital Library